Integrated circuit devices of this kind are most often used in applications where confidential information storing and processing security is essential. These can for example be electronic component-carrying cards for applications relating to the fields of health, mobile telephony, or also banking applications.
Such cards comprise an integrated circuit which conventionally includes a controller for (for example a central processing unit or CPU) managing and distributing, through bus lines, data or address information that is stored within the memory area of said cards. This integrated circuit having bus lines consumes electrical power, in particular when these bus lines are used to carry logical 1 information.
Also, the intensity of the electrical current used by an electronic component-carrying card varies with time, in particular because of the different values of data or addresses transiting over said bus lines in the card. The current change as a function of time is an electrical signature of the card's activity and therefore, analyzing said signature is indicative of said activity. Thereby, by means of an analysis of the electrical signature, forgers, for example, can easily follow a succession of operations contained in the different code blocks of the program of said card and therefore, can access the confidential information contained in this card.
In order to make the analysis of the electrical signature more complex to forgers, the state of the art suggests providing auxiliary devices for generating spurious signals that are added to the electrical signature of said electronic component-carrying card's activity. Although they make the electrical signature analysis more delicate, such auxiliary devices are slow because they monopolize some of the card's resources, which resources are already used for executing other operations specific to the card and consume more current because they include electronic components that require electrical power for their operation.